Bluelizardite, Na7(UO2)(SO4)4Cl(H2O)2, a new uranyl sulfate mineral from the Blue Lizard mine, San Juan County, Utah, USA

Abstract

*Corr esponding author Bluelizardite (IMA 2013-062), Na 7 (UO 2 )(SO 4 ) 4 Cl(H 2 O) 2 , is a new uranyl sulfate mineral from the Blue Lizard mine, San Juan County, Utah (USA). It was found in a sandstone matrix and is associated with chalcanthite, copiapite, ferrinatrite, gypsum, krohnkite, johannite, and several other new, unnamed Na- and Mg-containing uranyl sulfates. Bluelizardite is a supergene mineral formed by the post-mining weathering of uraninite. The mineral is monoclinic, C2/c, with a = 21.1507(6), b = 5.3469(12), c = 34.6711(9) A, β = 104.913(3)°, V = 3788.91(17) A 3 and Z = 8. Crystals are blades up to 0.4 mm long, flattened on {001}, elongated parallel to [010] and exhibiting the forms {100}, {001} and {111}. Bluel izardite is pale yellow and has a yellowish-white streak. It has good cleavage on {001} and uneven fracture. The Mohs hardness is estimated at 2. The calculated density based on the empirical formula is 3.116 g/cm 3 . Bluelizardite exhibits bright yellow-green fluorescence under both long- and short-wave UV radiation. The mineral is optically biaxial (–), with α = 1.515(1), β = 1.540(1) and γ = 1.545(1) (measured with white light). The measured 2V is 48(2)° and the calculated 2V is 47.6°. The mineral does not exhibit any dispersion or pleochroism. The optical orientation is X = b, Y ≈ a, Z ≈ c*. The empirical formula of bluelizardite is Na 6.94 (U 1.02 O 2 )(SO 4 ) 4.00 Cl 0.94 O 0.06 (H 2 O) 2 (based on 21 anions pfu). The Raman